Food abuse : Mealtimes, helplines and 'troubled' eating

Feeding children can be one of the most challenging and frustrating aspects of raising a family. This is often exacerbated by conflicting guidelines over what the ‘correct’ amount of food and ‘proper’ eating actually entails. The issue becomes muddier still when parents are accused of mistreating their children by not feeding them properly, or when eating becomes troubled in some way. Yet how are parents to ‘know’ how much food is enough and when their child is ‘full’? How is food negotiated on a daily level? In this chapter, we show how discursive psychology can provide a way of understanding these issues that goes beyond guidelines and measurements. It enables us to examine the practices within which food is negotiated and used to hold others accountable. Like the other chapters in this section of the book, eating practices can also be situations in which an asymmetry of competence is produced; where one party is treated as being a less-than-valid person (in the case of family practices, this is often the child). As we shall see later, the asymmetry can also be reversed, where one person (adult or child) can claim to have greater ‘access’ to concepts such as ‘appetite’ and ‘hunger’. Not only does this help us to understand the complexity of eating practices; it also highlights features of the parent/child relationshipi and the institutionality of families

Researcher’s Reactions to Compelled Disclosure of Scientific Information

Demands placed on researchers by subpoenas for scientific information are not necessarily any greater than those placed on other third-party recipients of subpoenas

Diffusion of a passive scalar from a no-slip boundary into a two-dimensional chaotic advection field

Using a time-periodic perturbation of a two-dimensional steady separation bubble on a plane no-slip boundary to generate chaotic particle trajectories in a localized region of an unbounded boundary layer flow, we study the impact of various geometrical structures that arise naturally in chaotic advection fields on the transport of a passive scalar from a local 'hot spot' on the no-slip boundary. We consider here the full advection-diffusion problem, though attention is restricted to the case of small scalar diffusion, or large Peclet number. In this regime, a certain one-dimensional unstable manifold is shown to be the dominant organizing structure in the distribution of the passive scalar. In general, it is found that the chaotic structures in the flow strongly influence the scalar distribution while, in contrast, the flux of passive scalar from the localized active no-slip surface is, to dominant order, independent of the overlying chaotic advection. Increasing the intensity of the chaotic advection by perturbing the velocity held further away from integrability results in more non-uniform scalar distributions, unlike the case in bounded flows where the chaotic advection leads to rapid homogenization of diffusive tracer. In the region of chaotic particle motion the scalar distribution attains an asymptotic state which is time-periodic, with the period the same as that of the time-dependent advection field. Some of these results are understood by using the shadowing property from dynamical systems theory. The shadowing property allows us to relate the advection-diffusion solution at large Peclet numbers to a fictitious zero-diffusivity or frozen-field solution, corresponding to infinitely large Peclet number. The zero-diffusivity solution is an unphysical quantity, but is found to be a powerful heuristic tool in understanding the role of small scalar diffusion. A novel feature in this problem is that the chaotic advection field is adjacent to a no-slip boundary. The interaction between the necessarily non-hyperbolic particle dynamics in a thin near-wall region and the strongly hyperbolic dynamics in the overlying chaotic advection field is found to have important consequences on the scalar distribution; that this is indeed the case is shown using shadowing. Comparisons are made throughout with the flux and the distributions of the passive scalar for the advection-diffusion problem corresponding to the steady, unperturbed, integrable advection field